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The magnetic and electrical properties of Cr3+ substituted nickel ferrite synthesized by wet chemical route have been studied. Particle size measured from x-ray diffraction and from transmission electron microscopy images confirms the nanosize dimension of prepared particles. Magnetic parameters such as coercivity and saturation magnetization are measured from vibrating sample magnetometer. Magnetization, ac susceptibility, electrical resistivity, and Mössbauer measurements were carried out. Electrical properties such as ac resistivity as a function of frequency and dc resistivity as a function of temperature were studied for various Cr3+ substitutions in nickel ferrite. The dielectric properties such as dielectric constant ([variant_greek_epsilon]′) and dielectric loss ([variant_greek_epsilon]″) were also studied. The dielectric constant and dielectric loss obtained for the ferrites prepared through wet chemical route posses a value lower than that of the ceramically prepared samples of the same composition. The resistivity obtained is higher than that of ferrite prepared by ceramic method. The dc resistivity increases with Cr3+ content x. The observed variation in resistivity is explained by Verwey hopping mechanism. The activation energy derived form the temperature variation in resistivity was found to increase with increasing concentration of Cr3+ ions. [ABSTRACT FROM AUTHOR]

In this work we study the magnetic states of ternary Ni 2 Cr Z ( Z  = Al, As, Bi, Ga, Ge, In, P, Pb, Sb, Si, Sn, Tl) Heusler alloys in comparison with Ni 2 Mn Z ones by ab initio methods. It is shown that the Ni-Mn based alloys are ferromagnetic. Contrary, the Ni-Cr based alloys with Z = Ga, In, Tl, Si, Ge, Sn, Pb are compensated aniferromagnets and with Z = Al, P, As, Sb, Bi are ferromagnets. The formation energy of alloys studied is calculated and stable compounds are predicted. The possible martensitic transitions in Ni-Mn and Ni-Cr based Heusler alloys are estimated. Within the Heisenberg model and Monte Carlo technique, the Curie temperatures are obtained. Theoretical results are compared with other theoretical end experimental results. [ABSTRACT FROM AUTHOR]

Previous electrical resistivity ( ρ ) and specific heat ( C P ) studies on the ternary (Cr 100 -x Al x ) 95 Mo 5 alloy system suggested that it harbours two quantum critical points (QCPs). This study reports comprehensive investigations of this alloy system through Seebeck coefficient ( S ) , thermal conductivity ( κ ) , magnetic susceptibility ( χ ) and neutron diffraction ( N D ) measurements in the concentration range 0 ≤  x  ≤ 8.6. The results of S and χ show that spin-density-wave (SDW) antiferromagnetism is suppressed to temperatures below 2 K for concentrations in the range 1.4 ≤  x  ≤ 4.4. Plots of d S / d T in the limit as T → 2 K depict two minima, i.e. just above x  = 1.4 and 4.4. This parameter has been used as a key indicator of quantum critical behaviour (QCB) in Cr alloys. Analyses against the Nordheim-Gorter relationship demonstrates a positive slope for the incommensurate (I) SDW alloys and a negative slope for the commensurate (C) SDW alloys. Extrapolations of these two slopes intercept at a concentration of 3.2 at.% Al indicating the occurrence of band structure modifications when Al is added into the Cr 95 Mo 5 base alloy. The Lorenz number ( L ) for the alloys with x  = 0 and 0.5 shows interesting anomalous behaviour associated with band structure effects and SDW magnetic ordering. N D measurements as a function of temperature confirm that alloys with x  < 1.4 order in the incommensurate (I) SDW phase whilst alloys with x  > 4.4 show commensurate (C) SDW order. Power law fits of the form T N ∝ 1.40 − x 0.35 ± 0.05 for the ISDW to P phase transition and T N ∝ x − 4.40 0.63 ± 0.03 for the P to CSDW phase transition rendered the critical exponents 0.35 ± 0.05 and 0.63 ± 0.03 respectively. Overall the results of S , κ , χ and N D corroborate the existence of two QCPs at x  ≈ 1.4 and 4.4. [ABSTRACT FROM AUTHOR]

Structural, dielectric and magnetic properties were investigated in the YCr 1−x Al x O 3 with 0 < x < 0.5 compositions. XRD and XPS studies show that the partial substitution of the Al 3+ ion decreases the cell volume of the orthorhombic structure without changes in the oxidation state of the Cr 3+ ions. We discuss two mechanisms that could have a significant influence on the magnetic properties. The first is related to local deformation occurring for x < 0.1 of Al content and the second is related to change of the electronic structure. The local deformation is controlled by the inclination of the octahedrons and the octahedral distortion having a strong effect on the T N and the coercive field at low Al concentrations. On the other hand, the decreasing of the magnetization values (M r and H c ) is ascribed to changes in the electronic structure, which is confirmed by a decreasing of the contribution of Cr 3d states at Fermi level due to increasing Al 3+ content. Thus, we analyzed and discussed that both mechanisms influence the electronic properties of the YCr 1−x Al x O 3 solid solution. [ABSTRACT FROM AUTHOR]

Thermoelectric effects are one of the promising ways to utilize waste heat. Novel approaches have appeared in recent decades aiming to enhance thermoelectric conversion. The theory of energy filtering of free carriers by inclusions is among the latest developed methods. Although the basic idea is clear, experimental evidence of this phenomenon is rare. Based on this concept, we searched suitable systems with stable structures showing energy filtering. Here, we report on the anomalous behavior of Cr-doped single-crystal Bi 2 Se 3 that indicates energy filtering. The solubility of chromium in Bi 2 Se 3 was studied, which is the key parameter in the formation process of inclusions. We present recent results on the effect of Cr-doping on the transport coefficients on a wide set of single crystalline samples. Magnetic measurements were used to corroborate the conclusions drawn from the transport and X-ray measurements. [ABSTRACT FROM AUTHOR]

Waste Nd–Fe–B sintered magnets (grade 33H) were recycled to manufacture anisotropic sintered magnets by adding Ce-rich alloys. The influences of additive amounts of Ce-rich alloys on the microstructure and magnetic properties of the recycled sintered magnets were investigated. It showed that the recycled sintered Nd–Fe–B magnet without Ce-rich alloy addition has rather lower density; the density of the magnet is slightly raised with increased sintering temperature, but the recycled magnet is prone to oxidation, even cracking. For recycled sintered magnets with Ce-rich alloy addition, the densities of the magnets are upgraded with increasing amounts of Ce-rich alloy, and the magnetic properties are obviously improved. This suggests that Ce-rich alloy plays the important role of sintering-aid in the densification of the recycled magnet. However, the coercivity ( $H_{{\text {cj}}} ) of the recycled magnets is decreased, when the additive amounts of Ce-rich alloy are over 8 wt.%. This is probably because excessive Ce-rich alloy addition can cause RE-rich phase aggregation at the triple grain boundary junctions, and deteriorate the microstructure of the recycled magnets. The recycled magnet with 5 wt.% Ce-rich alloy, sintered at 1080 °C, exhibits the following optimal magnetic properties: Br of 11.67 kGs; H{\text {cj}} of 18.94 kOe; and maximum energy product [(BH)\max ] of 33.1 MGOe. The magnetic properties of the recycled magnets are comparative to those of the waste magnets. Recycled magnets have a higher coercivity and perfect squareness of demagnetization curve ( Hk/H{\text {cj}} =0.972 ). [ABSTRACT FROM AUTHOR]

The structural and magnetic properties of Cr 2 O 3 have been studied by means of X-ray and neutron powder diffraction at high pressures up to 35 GPa. The lattice compression of the rhombohedral crystal structure of R 3 ¯ c symmetry is slightly anisotropic with anomaly in the pressure behavior of the c/a parameters ratio at P ≈ 20 GPa of presumably magnetic nature. The oxygen octahedra around chromium ions become more symmetric with close values of shared and unshared bonds under high pressure. The antiferromagnetic structure of Cr 2 O 3 remains stable in the studied pressure range up to 35 GPa. The pressure coefficient of the Néel temperature, (1/ T N )( dT N /dP ) = + 0.0091 GPa −1 , is significantly less in comparison with perovskite-like compounds containing Cr 3+ and Mn 4+ ions of similar electronic configuration. [ABSTRACT FROM AUTHOR]

Studies the occurrence of magnetic phases in iron-chromium and iron-cobalt compounds in the cesium-chlorine structure. Experimental details; Results and discussion.

Presents an experimental study of the magnetic phase transition temperatures of a chromium... iridium... alloy doped with vanadium and manganese. Experimental details; Results and discussion; Conclusion.

Examines the magnetoelasticity of chromium-gallium alloy single crystals at high pressures. Experimental methods; Hydrostatic pressure derivatives of the second-order elastic constants; Results; Conclusions.

Half-Cr-doped YMnO 3 single crystal films have been grown on YAlO 3 substrates with various compressive strains by using magneto sputtering and ex-situ annealing process. We report on effects of the compressive strain on their multiferroic properties. Anisotropic polarization shows a monotonous dependence on the compressive strain along the corresponding crystal axis. Furthermore, relative ratio between the remanent magnetic moments along the a - and c -axes is found to be strongly related to the lattice parameter c . These results are ascribed to the modification of magnetic structure under various compressive strains, i.e. , the compressive strains along the a- and c -axes predominantly stabilize the E -type antiferromagnetic and bc -cycloidal phases, respectively. [ABSTRACT FROM AUTHOR]

Shows that alloys of CrV alloys present a Curie-Weiss paramagnetism above the Neel temperature. Influence of the applied magnetic field on the magnetic properties of antiferromagnetic Cr alloys; Measurements of magnetic susceptibility.

Provides an explanation for the magnetic phase diagrams of all dilute Cr alloys. Consideration of coupled spin- and charge-density waves and a finite electron reservoir in a theoretical model; Paramagnetic to commensurate spin-density wave transition.

Fe-Si based alloys have been widely studied because of the excellent high frequency, soft magnetic properties, which are determined by the hyperfine structure of alloys. The evolution of the hyperfine structure and magnetic characteristics in an Fe-Si-Cr alloy with increasing heat treatment temperature have been studied. Fe-21.5 at.% Si-2 at.% Cr alloy powder was prepared and observed. The Fe-Si based alloys have three-step phase transitions under heat treatment. Hyperfine magnetic fields are increased after A2 ordered as the localized degree of 3d electrons decreased. Quadrupole splitting in alloys mostly originate from the paramagnetic phase, and the asymmetry of charge could increase the polarization response under high frequency microwaves. This could increase the microwave permittivity and paramagnetic phase ratio, which can contribute to better soft magnetic properties. The Mössbauer effective thickness of a Fe-Si-Cr alloy particles sample is calculated as 7.3345. Theoretical magnetic moments from first principle calculations and the Mössbauer result can be obtained and are consistent with experiment results. The formation of the DO3 phase could deteriorate soft magnetic properties of samples. High permeability of Fe-Si-Cr alloys can be obtained under heat treatment of the critical temperature when the DO3 phase starts to form. [ABSTRACT FROM AUTHOR]

In this work, some relations between crystal structure and magnetic ordering in CrCoFeNiAl HEAs are discussed in view of the KKR-CPA calculations. Remarkably, it is noticed that the transition between fcc and bcc phases in the analysed CrCoFeNixAl and CrCoFeNiAlx alloys is closely related to change in ordering of the local magnetic moments, namely the magnetic moment on Cr is either parallel (ferromagnetic) or antiparallel (ferrimagnetic) to the magnetic moments of other atoms (Co, Fe and Ni). On the whole, the theoretical diagram showing the fcc-bcc phase preference and their coexistence vs. alloy composition well corroborates with available experimental data. [ABSTRACT FROM AUTHOR]

The magnetic, dielectric, and magnetoelectric properties are investigated in the polycrystalline Cr2WO6. Under zero magnetic fields, no dielectric anomaly and electric polarization are observed in this compound. After magnetoelectric annealing, the magnetic-field-induced dielectric and pyroelectric current peaks simultaneously present around its Neel temperature and increase with increasing magnetic field, showing large magneto-dielectric and linear magnetoelectric effects in Cr2WO6. The origin of magnetoelectric effect in this compound is discussed. [ABSTRACT FROM AUTHOR]

The magnetic, dielectric, and magnetoelectric properties are investigated in the polycrystalline Cr2WO6. Under zero magnetic fields, no dielectric anomaly and electric polarization are observed in this compound. After magnetoelectric annealing, the magnetic-field-induced dielectric and pyroelectric current peaks simultaneously present around its Neel temperature and increase with increasing magnetic field, showing large magneto-dielectric and linear magnetoelectric effects in Cr2WO6. The origin of magnetoelectric effect in this compound is discussed. [ABSTRACT FROM AUTHOR]

Measurements of conduction electron spin resonance, temperature-dependent magnetization, small angle neutron scattering, and transmission electron microscopy were used for the analysis of chemical nonhomogeneity in austenitic steels with carbon + nitrogen or carbon only. It is shown that all studied steels are characterized by a nonhomogeneous distribution of alloying elements on the fine scale: from 3 to 5 nm in CrMnCN steels to about 30 nm in MnC Hadfield type steel. In the CN steels, their chemical homogeneity is improved by decreasing the C/N ratio. A ferromagnetic-type temperature behavior is observed in the CN steels at temperatures below 86 K, which is attributed to the blocking of magnetic moments of superparamagnetic clusters. The short-range decomposition of all studied steels results in a different splitting of dislocations, which corresponds to two different values of the stacking fault energy. [ABSTRACT FROM AUTHOR]

We report the magnetic properties of [Tb/Cr] 8 multilayer in which the Curie temperature( T C )of ferromagnetic Tb is much lower than the Néel temperature ( T N ) of antiferromagnetic Cr. An unexpected coercivity enhancement is observed at temperature above T N . Furthermore, the magnetic hysteresis loops measured after cooling in an applied field of 10 kOe exhibit “double hysteresis loops” behaviors at 156–216 K. The abnormal temperature dependence of coercivity is correlated with the spin-density wave structure of Cr, the competition between ferromagnetic and antiferromagnetic coupling at the interface of Tb and Cr layers as well as the interlayer coupling of the adjacent Tb layers. [ABSTRACT FROM AUTHOR]

Discusses pressure effects in alloys of chromium with particular attention to the effects of the magnetic interactions involved. Effects of pressure on the magnetic phase diagram; Effects of pressure on the elastic constants; Physical mechanisms involved in the softening of the lattice of the alloy.

Presents a magnetic phase diagram of the spin-density-wave CrFe alloy system from susceptibility measurements. Temperature dependence of magnetic susceptibility of alloys measured around the Neel transition.

Cu–Cr contact materials are widely used as medium- and high-voltage vacuum interrupters. The microstructure of these materials is critical in their performance: the finer structure they have, the better are their physical properties. A solid solution of Cu and Cr could significantly increase the performance of such contact materials. However, Cu and Cr are practically immiscible in the bulk phase. Based on first principles density functional theory we show here that the solubility of Cr in Cu is dramatically increased on Cu surfaces already at room temperature and Cu–Cr alloys are formed on both the Cu(111) and Cu(100) surfaces. We demonstrate that the origin of this phenomenon is the unique magnetic properties of Cr atoms near surfaces. [ABSTRACT FROM AUTHOR]

Presents information on a study of the effect of carbon and chromium diffusion on CoCrTa thin film recording media. Methodology of the experiment; Results of the study; Discussion.

A theoretical investigation into the electronic and thermodynamic properties of the high entropy alloy CrMnFeCoNi in nonmagnetic (NM) and ferrimagnetic (FIM) states based on first‐principles calculations has been implemented. Compared with the NM state, there is an obvious localized distribution of charges between Cr and Mn atoms with the lower valence electronic concentration (VEC) in the FIM state, showing covalent characters. Different spin‐polarized behaviors in compositional atoms have been proposed in the FIM state, suggesting the primary contribution to the total magnetic moment arises from the spin polarization of Fe d and Mn d states. Temperature‐dependent Debye temperature θD, heat capacity CV, and thermal expansion coefficient α as well as the total Helmholtz free energy F for both states have been investigated. Analysis of the contributions of configurational, electronic, magnetic, and vibrational free energy allows to infer the magnetic properties of the constituent atoms play an important role in the thermodynamics of CoCrFeMnNi high entropy alloy (HEA). For the CrMnFeCoNi high entropy alloy (HEA), the ferrimagnetic (FIM) state is energetically lower than the nonmagnetic (NM) state. The magnetic free energy Fmag is about two times of the electronic free energy Fel. The vibration free energy Fvib really starts to exceed configurational free energy Fconf until the temperature is above 600 K. [ABSTRACT FROM AUTHOR]